Featured Technical Soldering automotive wiring

I have always soldered the wire connections in my cars but I was recently told soldering wires makes them brittle and susceptible to breaking. I wire industrial machines for a living and hate using crimp connections whenever possible, especially butt connectors, they're butt ugly.

 

I use the steel butt connectors without the plastic cover. I top them with the marine (glue inside) shrink wrap. I would question if a soldered connection would be better than that. Anyway, it's worked for me. @Crazy Steve probably knows best.

 

For ring terminal connections I have crimped them on followed by sealing with solder and sharing a couple of layers of black shrink tubing to give it older look. I hate seeing multiple color wire ends.

 

I worked for a utility for 39 years in substations and used butt splices and crimp on connectors all that time, on my projects I've done the same with shrink tube over them. I know some people that crimp and then solder the joint but always thought that was overkill, there are solder connectors that you slip on then heat but I've always questioned whether that got hot enough to make a good solid connection.

 

Same thing on the ring terminals, buy them without the plastic and shrink wrap them. The plastic, even under the shrink wrap, looks like crap. You can't even see the metal ones. When I run out of them, I do cut the plastic off the ones I have lying around but I also cut my fingers a lot doing it.

 

I do like Bandit Billy .

 

Nothing is perfect, but a well soldered connection will usually last a lifetime, just as a well crimped one will.

however, a poorly soldered connection, or a poorly crimped one, will cause trouble.

Do you see a common theme here? Take the time to do it right, whatever method you choose.

 

Probably the biggest failure in crimped connectors is not using the correct crimp tool for the type of connector you are crimping.

 

Jim is right either is good if done correctly. A calibrated ratcheting crimping tool is best. A person can spend from 30 to several hundred dollars on a tool. I have a 3M tool (spendy) Klein makes an affordable tool 30 and 40 dollars.
https://www.amazon.com/Klein-Tools-...cphy=9019269&hvtargid=pla-2281435179298&psc=1
Dan

 

I’m in the crimp club. I use quality non insulated terminals, a professional rachet type crimp tool, and shrink tube. I also use serrated washers on anything that is terminated with a screw or hex nut.

 

The key to soldering is to only solder the terminal area, not up the wire. Heat it and dab a bit of solder on the end of the strand. Only enough that it sucks into the crimped terminal flaps, not farther up the wire.

 

I am in the same club, been doing the same thing with cutting the plastic off and using the metal. No wonder my fingers are all scared.

 

In both cases proper strain relief and moisture exclusion are the keys to longevity.

 

I use a wire wheel on a bench grinder and some pliers and the plastic ends buff right off.

 

If this means anything -

From a 20 year working experience - All aerospace (planes and satellites) use..."crimped" wire connections.

The only soldering is when assembling the circuit boards.

YES, solder DOES break with enough vibration (engine running...equals, vibration !), and time.

Mike

 

I use a pair of needle-nose pliers and hit the plastic on my belt sander, usually doesn't take much grinding to allow the sleeve to slip off. You don't even have to go through to the metal to get the plastic off

 

Should never solder stranded wire. Stranded means it seems vibration. Which means solder will eventually crack

 

This subject has beed discussed on this site many times over the years. The bottom line is this, a properly crimped wire end is better than a soldered joint. You will get the hard line believers that soldering is the way to go, but do your research and purchase the correct crimping tool and do it right.

 

Never shrink wrap a wire end. If the crimp or solder joint fails the shrink wrap will hold the wire in place and can cause an over heated joint. It can also make trouble shooting hard, as you can get a false reading when you try to "ring out" a connection. All one needs to do is an internet search on the subject and you can get all the fact's from electrical engineers.

 

This is what my wire connections look like:

 

My buddy let me use his g.m.training manual that covers repair including proper soldering techniques.

 

I soldered plenty of connections on aircraft ( the back of multi-pin connectors from the circuit board), the over 20 pin ones were the trickiest. The looms had crimped pins in the connectors. Both methods work, or else they wouldn't have used them.

 

I warm up the insulation with a cigarette lighter and just pull it off while warm (hot) don't burn your fingers.

 

I do the same thing and use vise grips or vice, razor blade and needle nose pliers.

I grew up wiring and soldering things.

On boats ALWAYS crimp with heat shrink, Ancor makes the best connectors / terminals with heat shrink as part of the connector.

The other way is to use a regular terminal with the plastic removed, then use marine grade heat shrink that seals up when heated.

For big battery terminals, I use a rigging crimper and then sweat solder into terminal, then use heat shrink.

If you dont have the type of heat shrink that also "seals" you can use liquid tape and then use heat shrink.

Solder can crack and separate with vibrations.
Might not happen this year but likely many years down the road.

This is why when I do any soldiering on boats it is on electronic component such as radar cables, sonar, sounders and stuff like that.


For cars, same as boats....

If you don't already know, buy a good crimper that puts a good "indent" into the terminal, ones that just flatten might have a use somewhere, but I have not found one.

 

Technical - Crimping Tutorial | The H.A.M.B.

Soldered field-installed connections have been illegal in all regulated electrical installations in the US for about 75 years except under specific conditions, i.e 'approved factory assemblies' or some mil-spec applications. Automotive has been unregulated, but even the OEMs avoid soldered connections wherever possible. That lack of regulation may be different now with EVs, as the voltages/currents they operate at can definitely be fatal.

Solder-only connections will fail under high heat conditions. Properly done crimps will not.

Well, this is a new one on me. I think somebody doesn't understand the purpose of the shrink tube. It's not there to insulate the connection (that's its secondary purpose), it's to provide strain relief and prevent it from breaking. Ideally, it should be as thick and at least as stiff as the wire insulation. If you're using one layer of the usual crappy thin tube the aftermarket usually sells, that's not enough. At the very least you should do multiple layers until you get the requisite stiffness, making sure you go at least 1/2" onto the wire if not more. There should be zero movement at the wire/connector joint. This is doubly important if you insist on soldering as the heat needed to get a good connection will also change the annealing of the copper, making it brittle and prone to breaking.

 

I usually solder all my terminal connections on my projects. Crimping is typically better, but you then need a bunch of expensive crimping tools. I did get a crimping tool/die for large gauge wire (1/0) type recently, and so much better and faster than soldering. The solder would typically wick up a couple inches and make that portion of the wire stiff which is not good.
I do recall having to solder some wires on a military project back in the day. We had an Amphenol/Bendix bulkhead power connector, again large gauge wires, and had to purchase a “solder pot” to melt the solder IIRC. Was a pain in the beginning since the workers were not familiar with the process.

 

When crimping terminals besides crimping to the wire properly, the terminal must also be crimped to the insulation. To provide strain relief on the wire crimp.
Most crimping tools have jaws for this.

 

How did the automotive factories do it on new cars? Let's use 1939 as a example.
Tens of thousands of miles of wear and tear and abuse.
Whatever method was good enough for O.E. should be good enough for the relatively low miles a hot rod is driven.

 

No wonder so many project cars don’t get finished, it’s not a space shuttle. As @squirrel said do either one properly and it’ll last your lifetime.

 

Agreed.

I worked in the telephone industry installing North Electric Crossbar and Stromberg Carlson XY Class 5 and Class 4 Central Offices. They are both electro-mechanical types and when operating there is vibration, but on a much smaller scale than in the automotive world. That vibration is there 24 hours a day, seven days a week, 365/366 days per year. We laced everything to limit movement. Solder connections I made in 1974 are still solid. We didn't have shrink tubing

I still solder and lace, and use shrink tubing at every terminal.